Table 1.
Baseline characteristics aby sex-specific quintiles of serum Insulin-Like Growth Factor 1 (IGF-1) (2008 and/or 2012), the English Longitudinal Study of Ageing (n = 4390).
| Sex-specific IGF-1 Quintileb | P value for difference | ||||||
|---|---|---|---|---|---|---|---|
| 1 | 2 | 3 | 4 | 5 | Linear | Quadratic | |
| Women % | 56.4 (1.7) | 54.3 (1.7) | 52.5 (1.8) | 57.7 (1.6) | 51.6 (1.7) | 0.25 | 0.89 |
| IGF-1, nmol/L, mean | 9.7 (0.1) | 13.3 (0.1) | 15.5 (0.1) | 18.1 (0.1) | 23.8 (0.1) | <0.0001 | <0.0001 |
| Age, years, mean | 66.7 (0.3) | 64.7 (0.3) | 63.8 (0.3) | 63.4 (0.3) | 62.3 (0.3) | <0.0001 | 0.02 |
| Height, cm, mean | 164.5 (0.3) | 166.0 (0.3) | 166.7 (0.3) | 166.4 (0.3) | 167.2 (0.3) | <0.0001 | 0.04 |
| BMI, kg/m2, mean | 28.8 (0.2) | 28.2 (0.2) | 28.1 (0.2) | 27.9 (0.2) | 27.9 (0.2) | <0.0001 | 0.08 |
| Diabetes, % | 10.7 (0.9) | 6.8 (0.9) | 6.5 (0.9) | 6.2 (0.9) | 8.6 (0.9) | 0.11 | 0.0002 |
| Cardiovascular disease, % | 8.4 (0.9) | 8.9 (0.9) | 6.8 (0.9) | 6.1 (0.8) | 5.6 (0.9) | 0.002 | 0.79 |
| Poor self-rated health, % | 23.4 (1.3) | 17.8 (1.3) | 17.7 (1.4) | 15.6 (1.3) | 18.4 (1.3) | 0.003 | 0.002 |
| Cognitive function memory score, mean | 16.3 (0.1) | 17.3 (0.1) | 17.2 (0.1) | 17.4 (0.1) | 17.3 (0.1) | <0.0001 | 0.0002 |
| High depression symptoms, % | 13.8 (1.1) | 8.6 (1.0) | 9.9 (1.1) | 12.1 (1.0) | 10.5 (1.1) | 0.34 | 0.04 |
| No educational qualification, % | 29.2 (1.4) | 22.7 (1.4) | 19.2 (1.5) | 21.6 (1.3) | 18.5 (1.4) | <0.0001 | 0.01 |
| Lowest wealth quintile, % | 27.4 (1.4) | 18.6 (1.3) | 17.6 (1.4) | 17.8 (1.3) | 18.7 (1.4) | <0.0001 | <0.0001 |
| Lives with a partner, % | 68.9 (1.5) | 75.3 (1.5) | 74.3 (1.5) | 73.8 (1.4) | 77.9 (1.5) | 0.0004 | 0.48 |
| Current smoking, % | 11.9 (1.1) | 10.5 (1.1) | 11.8 (1.1) | 11.3 (1.1) | 14.4 (1.1) | 0.09 | 0.08 |
| Sedentary/Low activity, % | 32.1 (1.4) | 22.4 (1.4) | 21.5 (1.5) | 21.2 (1.4) | 21.5 (1.4) | <0.0001 | 0.0001 |
| Daily alcohol intake, % | 23.8 (1.5) | 23.0 (1.5) | 25.5 (1.5) | 22.1 (1.4) | 23.0 (1.5) | 0.59 | 0.64 |
| Self-reported hearing impairment % | 18.1 (1.3) | 18.8 (1.3) | 17.4 (1.3) | 15.4 (1.2) | 16.3 (1.3) | 0.08 | 0.95 |
Abbreviations: IGF-1, insulin-like growth factor 1; BMI, body mass index. aValues are means or percentages (standard error). bIGF-1 (nmol/L) range in each quintile: 3–12.5; 13–15; 15.5–17.5; 18–20.5; 21–52 (men) and 4–11; 11.5–13.5; 14–15.5; 16–19; 19.5–43 (women).